Secondary batteries, such as lead-acid batteries, are generally formed having a plastic or polypropylene container which houses battery plates and electrolyte that carry out the electrochemical reaction of the battery. A cover is mounted on the container at the upper edges. Many such batteries utilize containers with cell dividers or partitions which divide the container into several compartments. The compartments hold the battery plates or plate stacks. The partitions or cell dividers are generally formed of a rectangular shape and have an upper edge which is aligned, or co-terminus with, or below the upper edge of the container. In such battery assemblies, the height of the container wall and the partition wall determines the maximum height of the battery plate or grid. As a result, the size of the grid and corresponding performance of the grid is limited by the container height.